Trachemys dorbigni

D'Orbigny's slider or the black-bellied slider (Trachemys dorbigni ), commonly known in Brazil as tartaruga-tigre or tartaruga-tigre-d'água (which means tiger turtle and water tiger turtle in Portuguese), is a species of water turtle in the family Emydidae. The species is found in southern Brazil, northeastern Argentina, and Uruguay. One subspecies (in addition to the nominate subspecies) is distinguished, Trachemys dorbigni brasiliensis. The specific name, dorbigni, is in honor of French naturalist Alcide d'Orbigny. The form of the plastron determines its gender. After a few years of life, show differences between male and female. Males have a penis that is inserted into the tail. It becomes apparent only during the mating season when it is inserted into the female's cloaca. D'Orbigny's slider has a life span between 30 to 100 years in captivity. They are usually found in water bodies such as lakes, marshes, streams and rivers. They have a preference for waters with low or moderate currents, soft bottoms and abundant aquatic vegetation. Babies are born weighing 11 grams (0.39 oz) with a 3.5 centimetres (1.4 in) carapace. The average growth rate is about 3 centimetres (1.2 in) per year on wild, but in captivity it can grow faster being able to grow over 9 centimetres (3.5 in) in a year. The females can grow up to 30 centimetres (12 in) carapace and weight over 2.7 kilograms (6.0 lb), while the male can only grow 25 centimetres (9.8 in) carapace. When the males reach sexual maturity (after 2 years), they acquire a dark color while the females keep the same green after maturity (at 5 years). The sex identification is only possible when adult, at 5 or 6 years. The female is bigger and may reach 30 centimetres (12 in) in length and has the bottom of the shell (plastron) slightly convex so as to provide more space for eggs. The male reaches 20 centimetres (7.9 in)to 25 centimetres (9.8 in)and has a longer and bulky tail, furthermore, the male bottom of the shell is straight or slightly concave to fit better upon females. The male's cloaca is located 2/3 the distance between the tail beginning and the shell, while the female is very close to the shell. Females produce an average of 10 eggs per buried nest; usually they bury two nests per season. Incubation ranges from 2 to 4 months. The eggs are laid under approximately 10 centimetres (3.9 in) of sand. The eggs are white-colored. Each egg on average measures 39.3 millimetres (1.55 in) in length and 25.8 millimetres (1.02 in) in width, weighing on average 14.9 grams (0.53 oz).